A Breach Between Worlds

 is a quest in Tyranny.

Synopsis
You have learned that the rebels are searching the Blade Grave Oldwalls for the remains of an Unbroken Regent, one believed to hold the Steadfast Insignia. This artifact is said to have the power to resist the fierce winds of Kyros' Edict of Storms, and may be your way into Sentinel Stand Keep.

Walkthrough

 * Travel to the Oldwalls Breach along the Blade Grave Oldwalls to locate the Unbroken soldiers hunting for the Steadfast Insignia. If not on the Rebel path, you'll have to kill them. Talk to Hieronymus.
 * Hieronymus said the item you need to get into the Oldwalls is on the body of an Unbroken soldier who fell in battle, southeast of the Breach. Find his body and get the Garn Torchkey. It's to the other side.
 * Enter Blade Grave Oldwalls - Central. Make your way to the center, where the Havoc is located. Pick up the Humming Keystone from Scribe Javala's body. Install it in the lower left receptacle.
 * Move back, press the button by the entrance to the chamber to activate the way upstairs.
 * Enter the right-hand corridor, open the room to the south with the wall switch. Clear the Bane. Use the red torchkey on the beacon, use the wall switch. Acquire the Cold Keystone from the freshly opened room.
 * On the way to Blade Grave Oldwalls - West, enter the upper left chamber. Cross the bridge, and pick up the Stone of Elucidation. Use a piece of rubble found nearby to weigh the altar down to return.
 * In the Western section, pick up the Saphir Torchkey at the altar. Use it to access the upper levels and get the Heavy Keystone from the chest.
 * Head to Blade Grave Oldwalls - East. You want to reach the far eastern part of the level, with the beacon that requires a torchkey. Use it to open an altar room and acquire the Ambir Torchkey.
 * Head to the beacon room on the opposite end of this level. Use the crystals on the beacons to unlock the room with the keystones. The correct order is Blue, Red, Yellow. Failing to use the correct color will summon increasingly powerful Bane, up to two Malices. Pick up the Bright Keystone in the room beyond the corridor.
 * Return to the imprisoned Havoc. Rest if required. Insert the keystones in a clockwise direction starting from the humming keystone.
 * Use the floor switch to release the Havoc. Defeat it. Loot the creature.
 * Approach the First Regent's corpse and claim the Steadfast Insignia.
 * Return to Graven Ashe (Disfavored path), Mattias at Duskwatch Fort (Rebel path), or head for Sentinel Keep (Anarchist, Chorus paths).
 * A group of Disfavored will greet you outside. If not allied to the Disfavored, you have to fight them.